Updated iPhone review to the newer SKStoreReviewController

* As mentioned in #32 , the older SKStoreReviewController is deprecated and we should be using the newer ones recommended by apple.
* I followed the code recommended in the [Apple Forums](https://developer.apple.com/forums/thread/652157?answerId=653723022#653723022) in order to figure out the solution

**Testing**
------
* Tested in iPhone 8 Simulator running iOS 15.2
* Created a blank native app in Xamarin iOS and put in the code as you can see in the screenshots and i was able to see the review popup successfully without any exceptions

src/StoreReview.Plugin/StoreReviewImplementation.apple.cs

@@ -6,6 +6,7 @@
 using System.Threading.Tasks;
 #if !__MACOS__
 using UIKit;
+using System.Linq;
 #endif
 using StoreKit;
 
@@ -79,6 +80,15 @@ public Task RequestReview(bool testMode)
 #if __IOS__
             if (IsiOS103)
             {
+				if (IsiOS14)
+				{
+					var windowScene = UIApplication.SharedApplication.ConnectedScenes.ToArray<UIScene>()?.First(x => x.ActivationState == UISceneActivationState.ForegroundActive) as UIWindowScene;
+					if (windowScene != null)
+					{
+						SKStoreReviewController.RequestReview(windowScene);
+						return;
+					}
+				}
                 SKStoreReviewController.RequestReview();
             }
 #elif __MACOS__
@@ -105,6 +115,7 @@ internal static Version ParseVersion(string version)
 
 #if __IOS__
 		bool IsiOS103 => UIDevice.CurrentDevice.CheckSystemVersion(10, 3);
+		bool IsiOS14 => UIDevice.CurrentDevice.CheckSystemVersion(14, 0);
 #endif
 
 	}